Fuel Injector Group "D" Supply Voltage Circuit Low
P2156 indicates the engine control module detected low voltage in the fuel injector Group D circuit, which prevents proper electronic control of fuel delivery to those cylinders. This occurs when the voltage supplied to the injectors in this group falls below the manufacturer's specified threshold, disrupting the precise fuel injection timing and quantity needed for efficient combustion.
What You Might Notice
- Check Engine light illuminated
- Rough idle or engine surging
- Reduced fuel economy
- Loss of power during acceleration
- Possible engine misfires in affected cylinders
Most Common Causes
- 1
Faulty fuel injector in Group D
A fuel injector in the Group D circuit may have failed electrically, causing incorrect voltage readings. This is the most common cause of this code.
- 2
Corroded or loose injector connectors
Poor electrical connections at the fuel injector connectors create resistance that reduces voltage to the injector coils. Corrosion or loose pins prevent proper circuit operation.
- 3
Damaged wiring in injector circuit
Broken, pinched, or frayed wiring between the engine control module and the Group D fuel injectors causes voltage loss. Rodent damage or improper repairs can compromise the circuit.
- 4
Fuel injector driver module failure
The PCM's internal fuel injector driver circuit may be faulty, preventing it from supplying adequate voltage to the Group D injectors. This requires PCM replacement or reprogramming.
How to Diagnose It
- 1
Check Faulty fuel injector in Group D — A fuel injector in the Group D circuit may have failed electrically, causing incorrect voltage readings. This is the most common cause of this code.
- 2
Check Corroded or loose injector connectors — Poor electrical connections at the fuel injector connectors create resistance that reduces voltage to the injector coils. Corrosion or loose pins prevent proper circuit operation.
- 3
Check Damaged wiring in injector circuit — Broken, pinched, or frayed wiring between the engine control module and the Group D fuel injectors causes voltage loss. Rodent damage or improper repairs can compromise the circuit.
- 4
Check Fuel injector driver module failure — The PCM's internal fuel injector driver circuit may be faulty, preventing it from supplying adequate voltage to the Group D injectors. This requires PCM replacement or reprogramming.
How to Fix It
- 1
Inspect and clean fuel injector connectors
Locate the Group D fuel injector connectors and disconnect them to inspect for corrosion, looseness, or damage. Clean the connectors with contact cleaner and ensure pins are fully seated. Reconnect and retest with a scan tool.
- 2
Replace faulty fuel injector
Use a multimeter to test the resistance of each fuel injector in Group D. Replace any injector that reads outside the manufacturer's specification (typically 12-16 ohms). Remove the fuel rail assembly to access the injectors.
- 3
Repair or replace damaged wiring
Inspect the wiring harness from the PCM to the Group D fuel injectors for breaks, pinches, or corrosion. Repair damaged sections with proper automotive-grade wire connectors or replace the entire injector harness if extensively damaged.
- 4
Test and reprogram PCM
If voltage is confirmed at connectors and injectors test good, the PCM fuel injector driver circuit may be faulty. Use a diagnostic scanner to read live injector voltage data and verify proper signals. Reprogram or replace the PCM if defective.
Need a deeper diagnosis?
Search for related repair guides or browse by system.